Delustered artificial silk and the method of manufacturing same



Patented Mar. 11, 1941 UNITED STATES DELUSTERED ARTIFICIAL SILKAND THE'IWETHOD OF MANUFACTURING SAME Delaware No Drawing. Application March8,1938, :SerialNo..194,599

6 Claims.

The present invention relates to an-improved method for reducing oreliminating'the lustero'f I artificial silk and to the improved productobtained thereby.

The normal artificial'silk fibers are usually as clear as glass andhighly lustrous, both of which properties are undesirable for manypurposes, such as garments of various kinds. For such purposes, thefiber is mademore or less opaque. This is accomplished by mixing inertoils of various kinds intothe spinning solution, such oils beingdissolved out after the precipitation or solidification of the yarn,whereby'the'surface of the yarn becomes irregular with resultingreduction in luster. The luster has heretofore also-been reduced byadding to the 'spinning'solution a white filling material, suchraspowdered asbestos, barium sulphate, ortitanium dioxide,

these added materials opaque.

'The addition of these known fillingimaterials has a number ofdisadvantages. In the :Ifirst placefthe filling material, especially inthe-case of the heavy mineral substances, tends "to precipitate out inthe vessels containing thespinning liquid, and the precipitated:material clogs the filter and the spinning or-extrusion nozzles. Aperhaps more serious objection'arisesfrom 'the fact .that theseadditions represent dead "material in the-yarn, bein'g of an entirelydifferent character from the cellulosic substance of the 'yarn'andincompatible therewith, andas azresult considerably reduce the strengthof the yarn, particularly as no natural :bond -forms between theopaoifying ordelusteringagent and the yarn substance.

A further disadvantage which arises in .the case of mineral fillers,likebariumsulphate and titanium dioxide, is that they increaserthe averagespecific gravity of "the yarn, and'tend to -make it brittleand alsoharsh to the touch.

A still ifurther disadvantage of the use of mineral fillers or .oflikematerial, is that such rendering the yarn material is not readilycapable'iof tabsorbing dyes or other material, whereas itheietype ofmaterial contemplated for use by me as the fillersrea'dily absorbs dyesand coloring. The product will thus be capable of having impartedthereto a uniform color throughout the silk yarn and filler. The fillercan thus be dyed before the dyeing of the silk, and therefore variouscolor effects, combinations of colors in fillers and yarn, may beproduced.

The present invention is based on the concept that it would be highlydesirable to in- PATENT OFF-ICE 7 corporate in "the artificial silk adelustering-filling material having as nearly as possible theproperties, aside from luster, of the yarn subthe artificial silk matrixbutis at thersame time characterized by the feature that it :does-ariotswell in water although it is capable'of' absorbing water. 'I thusobtain a 'delusteredartificial:silk which retains its strength evenin'wetting and shows 'no tendency to swell :by *reason' of the nature ofthe delustering agent. Thiscellulosic filleris of approximately the same'specificgravity as the artificial silk, so that 'delustering'of thelatter can be effected without fat the :same time loading it. Moreover,the :cellulosic filler is of approximatelythe same texturewand feel asthe artificial silk, resembling the latter in these respects much moreclosely than the known inorganic fillers. Also,-the 'cellulosic materialrepresents a very cheap filler, and moreover, shows a tendency to formsome kind of combination or association with the substance of theartificial fiber, 'so that it does "not existin the finished fiber, atleast no'wholly, as separate particles foreign to the substance of :theyarn and tending to weaken the-latter, but rather as a combinedcomponent which even acts to strengthenthe yarn.

I have found that a powdered cellulose prepared as described in .my"copending. application,

Ser. No. 187,965, filed January '31, 1938, .con-.

stitutes' a superior delustering agent for :artificial silk "because itpossesses "to a'marked =degree the desirable properties "above referredto.

'Thispowdered cellulose, as described in said: ap-

plication, maybe prepared by subjecting-cellu- .lose to the actionof'xaqueous formaldehyde in the presence of a strongacidiikernitrimacid;at

elevated temperatures, and with or "wit-houtsimultaneous drying, theproduct being ultimately dried if it has previously been subjected tothe above-mentioned solution at the elevated temperatures but withoutdrying. Cellulose so treated is capable of being easily ground to afineness of 200 mesh and even finer without hydrating the cellulose.This ground cellulose is it! duced with known fillers.

dehyde and a small amount of acid, suchas abath consisting of 100 kg. of40% formaldehyde,

/2 kg. of concentrated nitric acid and 50 kg. of

water, after which the excess liquidis withdrawn 15 by pressing,centrifuge, or otherwise, and the material then heated to a temperaturewhich is preferably above 100 C. but not so high; as, to injure thematerial, and preferably with si;-j

multaneous drying. A temperature of the order 20 of 120 C. has beenfound to be highlysatisfactory. If the material is not dried during theheating (during which the reaction on the cellulose occurs) it is vthendried and pulverized in any order, the reaction being continued until a25 highly brittle product is obtained. This material can be pulverizedto a condition of fineness resembling starch powder. l 1

The powdered cellulose employed by me does not tend to precipitate fromthe spinning solu- 30 tion during any stage in the manufacture of theyarn, being of approximately the same specific gravity as the artificialfiber, and therefore does not clogthefilters or the nozzles.

In the case of artificial yarn produced by an 35 alkaline process, as inthe case of viscose yarn, there occurs a cementing of the cellulosefiller particles with the spinning solution during the spinning,resulting in the production of a-yarn which is considerably strongerthan one pro- With non-alkaline spinning solutions, the added cellulosicfilling material absorbs the solvent by reason of its porosity andthereby becomes intimately incorporated with the cellulosic substance ofthe spin- 45 ning solution during the mixing, extrusion andprecipitation or drying. In these non-alkaline processes, there islikewise obtained an artificial silk yarn having a pleasingly subduedluster.

The amount of cellulosic filling material to be 50 employed in any givencase will depend largely upon the degree of delustering desired.Ordinarily, an amount of cellulosic ,filler equal to about 2 to 3% byweight of the artificial silk will be sufficient to reduce the highluster of 55 artificial silk to that of natural silk. The maximum sizeof the particles may vary within rather wide'limits, except they shouldnot reach such a size as would be liable to clog the nozzles which areto be employed with the particular cellu- 5 losic composition.Cellulosic powders having a maximum particle size corresponding to about200 mesh, or smaller, have been found to give very satisfactory results.In general, the particle size shouldbe 'of the order of that employed in65 the case of the known mineral fillers like barium sulphate ortitanium dioxide, for example, about 50 to100 microns.

The cellulosic filling-material may be mixed with the spinning solutionin substantially the same way as the known filling materials nowemployed. Thus, the mixing may take place at room temperature. It may bedesirable in some instances to keep the filling material in contact withthe spinning solution fora somewhat longer period of time than is thecase with mineral fillers, in order to enable the filler to becomechemically associated with the spinning solution, but ordinarily, thetime normally required for preparing. the mixture and extruding andprecipitating or drying it, will be sufiicient to produce the desiredeffect.

Asalreadyfindicated, the cellulosic filler, according to'the" invention,may be employed with different kinds 'of artificial silks, includingviscose, cellulose acetate, cellulose ether and cellulose nitrate silks.It will be obvious that the cellulosic filler can, if desired, be used,in conjunction with known fillers. Other variations may be resorted towithin the scope of the appended claims without departing from theprinciples of the invention.

Also, the invention is obviously applicable 'to materials of anycellulosic form, whether artificialsilk, or cellulosic products, fibrousor other, for instance, in the form of ribbon, films, etc.

I claim: 1. An artificial silk material of reduced luster, havingincorporated therein a ground cellulosic material which has beenrendered brittle by heating'with aqueous formaldehyde and mineral acidfollowed by' drying and characterized by substantial freedom fromswelling onwetting with water. i I Y 2. An artificial silk of reducedluster, having incorporated therein a powdered formaldehydeandacid-pretreated cellulose characterized by substantial freedom fromswelling on wetting with water. 3. An artificial silk of reduced luster,having incorporated therein a comminuted cellulosic filler of a maximumparticle size of the order of 50 to 100 microns and produced by heatingcellulose with formaldehyde and a strong acid to a temperature of about120 C. followed by drying and grinding.

4. An artificial silk of reduced luster, having incorporated thereinabout 2 to 3% of powdered cellulose'of a maximum particle size of about100 microns and produced by heating cellulose with formaldehyde andnitric acid to a temperature of about 120 C. followed by drying andgrinding in any order.

5; An acetate silk of reduced luster, having incorporated therein apowdered, formaldehydeand acid-pretreated cellulose characterized bysubstantial freedom from swelling on wetting with water.

6. Artificial silk fibers having suspended therein about 2m 3% of theirweight of finely-powdered cellulose prepared by heating cellulose fiberswith aqueous formaldehyde and a small proportion of mineral acid until abrittle product is obtained, followed by drying and grinding in anyorder. I

' JULIUS KANTOROWICZ.

